Peptides as drugs
Since peptides play a crucial role in the fundamental physiological and biochemical functions of life, they have for decades now attracted much attention for their potential therapeutic use.
Compared with small chemical entity drugs, peptide based drugs possess certain favorable characteristics, including:
- Higher potency; peptide based drugs generally are very active on their target receptor, which translates into a high effect at a low dose;
- Higher selectivity; peptides have a very tight fit to their receptors, which makes them much more selective than smaller molecules. This means that peptides tend to bind only to their target receptor and therefore are less likely to be associated with serious adverse side effects;
- Naturally occurring biologics – better safety: Peptides are naturally degraded in the blood stream by circulating enzymes to their component amino acids. As these are natural biological products, peptide drugs are also associated with less accumulation in body tissue and fewer toxicity findings – also owing to their low doses
On the other hand, there are also important challenges associated with the use of peptides as the basis for therapeutic products:
- Short-lived: Many natural peptides have a very short half-life; which means that they generally act in the body for only a very short time, 2-30 minutes, before being broken down for
reuse of the amino acids as building blocks. For therapeutic use, native peptideswould require constant administration.
- Cannot be administered orally: Most peptides must be administered via injection, because oral administration would lead to degradation and destruction by the digestive system, cleaving the molecules up into separate and therapeutically ineffective amino-acids
- Low product stability: Many naturally occurring peptides can not be stored in aqueous solution for more than a few days, and is thus not generally convenient to use as drugs.